Cycloid press

ABSTRACT

A press includes a reciprocating slide having a connecting rod which is fastened to a reciprocating mechanism through a connecting rod assembly. The assembly moves in the path of a three-lobe hypocycloid.

United States Patent [191 Pim [ Nov. 19, 1974 CYCLOID PRESS [75] Inventor: Norman L. Pim, Salem, Ohio [73] Assignee: Gulf & Western Manufacturing Company (Hastings), Hastings, Mich.

[22] Filed: June 4, 1973 211 App]. No.: 366,982

[52] US. Cl. 74/52 [51] Int. Cl. F16h 37/12 [58] Field of Search 74/52, 804

[56] References Cited UNITED STATES PATENTS 10/1899 Woodward 74/52 Baldwin et al. 74/52 Marchou 74/52 Ehrhardt 74/804 Beck 74/804 Primary Examiner-Samuel Scott Assistant Examiner-Wesley S. Ratliff, Jr.

ABSTRACT 6 Claims, 6 Drawing Figures PATENTEL rm 1 91914 who 3.848.472

FIG. I

PATEME, my 1 91974 SHEEI 2 [IF 3 FIG. 4

FIG. 3

FIG. 5

PAIENTEL MN I 9 I974 RETURN SHEET 30F 3 WORK ADVANCE HMOELLS TIME FIG. 6

CYCLOID PRESS BACKGROUND OF THE INVENTION This application pertains to the art of presses and more particularly to an improved reciprocating mechanism for presses. Although the invention is particularly applicable to presses and will be described with particular reference thereto, it will be appreciated that the invention has broader applications and the reciprocating mechanism may be used in other devices.

Mechanical presses commonly include a reciprocating slide having a connecting rod which is fastened to a reciprocating mechanism. In known pressesof this type, the work stroke is a small fraction of the total press cycle. This limits the number of cycles per minute such a press can make.

Many different prior art arrangements have been attempted for increasing the number of strokes per minute which a mechanical press can make. U.S. Pat. No. 2,338,352 to Paque discloses a press having a reciprocating mechanism which moves the connecting rod connection in a straight-line hypocycloid. The Paque mechanism is constructed in the press rather than being a part of the connecting rod connection. This makes the mechanism very complicated. A straight-line hypocycloid does not offer much improved cycling time over other reciprocating mechanisms.

U.S. Pat. No. 3,158,057 to Hartman discloses a cutting device including a reciprocating mechanism for moving a connection in the path of a three-lobe hypocycloid. However, the Hartman mechanism is separate from the connecting rod assembly which is very complicated and requires an inordinate amount of space.

SUMMARY OF THE INVENTION The press includes areciprocating slide secured to a connecting rod assembly for moving in the path of a three-lobe hypocycloid. A three-lobe hypocycloid is a curve traced by a point on the circumference of a small circle rolling internally on the circumference of a larger circle. With such a motion, the press may be adjusted between zero stroke and maximum stroke in a very simple manner.

In accordance with one arrangement, the reciprocating mechanism includes inner and outer eccentrics in the connecting rod assembly. The inner eccentric is rotatably driven about a fixed center in a predetermined direction. The outer eccentric is rotatable about the inner eccentric. An epicyclic gear train rotatably drivesthe outer eccentric about the inner eccentric in a direction opposite to the predetermined direction. The epicyclic gear train includes a sun gear having a sun gear center coincidental with the fixed center about which the inner center rotates. The epicyclic gear train also includes a pinion gear mounted on the outer eccentric in engagement with the sun gear. Rotation of the inner eccentric causes the pinion gear to roll around the'sun gear for moving the connection in the path of a threenecting rodconnection for moving the connection in the path of a three-lobe hypocycloid.

It is a further object of the present invention to provide an improved reciprocating mechanism which moves the connection in the path of a three-lobe hypo cycloid and is adjustable for shifting the path of the hypocycloid.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 3 shows the path in which the connection moves;

FIG. 4 shows a shifted path in which the connection moves;

FIG. 5 shows another shifted path in which the connection moves; and,

FIG. 6 is a motion graph for the improved reciprocatingmechanism of the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawings, wherein the showings arefor purposes of illustrating a preferred embodiment of the invention only and not for purposes of limiting same, FIG. 1 shows a mechanical press A having the improved reciprocating mechanism of the present invention incorporated therein. Press A includes a frame B havinga bed C supported thereon. A slide D is reciprocatingly supported in gibbing in a known manner for substantially vertical reciprocating movement relative to frame B toward and away from bed C.

A large flywheel E is rotatably driven by a motor in a known manner and is fixed to a drive shaft 12 rotatably journaled in frame B. Shaft 12 rotates about a fixed center or longitudinal axis 14. Shaft 12 has an eccentric l6'thereon which is eccentric relative to fixed center 14 by distance 18'from axis 24.

Inner eccentric 16 is rotatably journaled as at 20 to an outer eccentric 22. Outer eccentric 22 is eccentric relative to longitudinal axis 24 of inner eccentric 16 by distance 26. Outer eccentric 22 has a small pinion gear 30 secured to one flat face thereof as by bolts 32. The central axis of pinion gear 30 coincides with longitudinal axis 24 of inner eccentric 16..A sun gear 36 is secured to frame B as by bolts 38 and has its center coincidental with fixed center 14. Bolts 38 must be removed in order to adjust sun gear 36. Pinion gear 30 engages inner teeth on sun gear 36. Sun gear 36 may have worm wheel teeth as at 40 formed on the outer periphery thereof. A worm gear 42 rotatably journaledin frame B engages worm wheel teeth 40.

Generally C-shaped connecting members 50and 52 have outer flanges 54 and 56 clamped together as by bolt and nut assemblies 58. Generally C-shaped members 50and 52 have generally U-shaped cross-sectional configurations to provide a cylindrical pocketrotatably receiving outer eccentric 22 as shown in FIG. 1. Suitable bearings may be provided in a known manner. Connecting member 52 has a bottom projection 60 pinned as at 62 to the upper end of a connecting rod 64 which in turn is connected by a swivel connection at 66 to slide D.

It will be recognized that inner and outer eccentrics 16 and 22, and pinion gear 30, all form a part of the assembly with connecting members 50 and 52 for connecting rod 64 with power drive shaft 12. Pinion gear 30 and sun gear 36 define an epicyclic gear train.

When shaft 12 is rotated in a predetermined direction, movement is also imparted to outer eccentric 22. Pinion gear 30 then rolls around sun gear 36 on the inner periphery thereof for rotating outer eccentric 22 about inner eccentric 16 in a direction opposite to the direction in which inner eccentric 16 is rotated. Therefore, the defined assembly moves in the path of a threelobe hypocycloid. This path is indicated in FIG. 3, which path may be considered as including a dwell portion 70, a work stroke portion 72, and a return stroke portion 74. With fixed center 14 vertically aligned with axis 24 as shown in FIG. 2, the path taken by the connection is that generally shown in FIG. 3.Worm gear 42 may be rotated for rotating sum gear 36. Rotation of sun gear 36 will shift axis 24 out of vertical alignment with fixed center 14. This will shift the path of the three-lobe hypocycloid, such as to a position shown in FIG. 4. Dwell portion 70 is then advance stroke, while work stroke portion 72 is shorter in a vertical direction. Further adjustment may be made until dwell portion 70 is as shown in FIG. wherein no movement at all will be imparted to slide D. Infinite adjustment between maximum stroke shown in FIG. 3 and zero stroke shown in FIG. 5 may be obtained simply by rotating sun gear 36.

FlG. 6 shows a motion graph for one cycle of a press having the improved reciprocating mechanism of the present invention incorporated therein. Stroke is plotted on the vertical axis of the graph, while time is plotted on the horizontal axis of the graph. Advance, work and return strokes all take up one third of the total press cycle.

Many different dimensions may be used with the described arrangment. One arrangement will be described for purposes of illustration. It will be recognized that either inner eccentric 16 or outer eccentric 22 may be the larger one. In the specific arrangement shown, outer eccentric 22 has a larger eccentricity than inner eccentric 16. However, this relationship can be reversed. Where one of the eccentrics has a radius 18 of l, the other eccentric will have a radius 26 of 2. If the length of the connection and connecting rod is 7, the total stroke of the press, when adjusted to dwell, will be 4. When the eccentrics are adjusted to give a work stroke instead of dwell, the total stroke of the press is increased. The work stroke is continually adjustable from zero to approximately two and one-half. This adjustment proportionally increases the total stroke of the press from 4 to approximately 5. With the arrangement described, inner short radius eccentric 16 will make two revolutions to each one of larger outer eccentric 22. This is three rerevolutions in relation to one another for each cycle of the press.

The length of eccentrics l6 and 22 may be reversed.

With such an arrangement, inner eccentric 16 would 5 then make one revolution for each two revolutions of outer eccentric 22. Itwould still be three revolutions with relation to one another for each press cycle. When inner eccentric 16 is the short radius eccentric, the ratio between gears 30 and 36 is one and one-half to one. When inner eccentric 16 is the long radius eccentric, the ratio between gears 30 and 36 should be three to one.

In single eccentric presses, the press cycle starts at the top of reciprocating motion and consists of two phases, which are advance or downstroke phase, and return or upstroke phase. These two phases are approximately equal time, and each consists of accelerated and decelerated slide motion. With the improved mechanism of the present invention, the reciprocating motion is divided into three phases of approximately equal time. One phase is advance downstroke, the second phase, depending on the adjustment of the sun gear, is either no motion dwell or down workstroke. The third phase is return upstroke. The third phase may be equal in length to the sum of the first two phases. if a press cycle is considered to be based on workstroke time, the cycle of a press having the mechanism of the present invention therein will be shorter than the cycle of a single eccentric press. Therefore, a press having the reciprocating mechanism of the present invention will be capable of more strokes per minute.

Although the invention has been shown and described with respect to a preferred embodiment, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the claims.

Having thus described my invention, I claim:

1. In a press including a rotatable power shaft for reciprocating a slide connected with the power shaft through a connecting rod and connecting rod assembly said connecting rod assembly including inner and outer eccentrics, said inner eccentric being rotatably driven about a fixed center in a predetermined direction, an epicyclic gear train for rotatably driving said outer eccentric in a direction opposite to said predetermined direction about said inner eccentric, said gear train including a sun gear having a sun gear center coincidental with said fixed center, said sun gear being fixedly mounted against rotation, said gear train including a pinion gear mounted on said outer eccentric in engagement with said sun gear, said eccentrics and gear train being dimensioned for moving said connection substantially in the path of a three-lobe hypocycloid when said inner eccentric is rotatably driven.

2. The press of claim 1 wherein said sun gear is rotatably adjustable about said sun gear center for rotatably shifting the path of the three-lobe hypocycloid.

3. The press of claim 1 wherein said inner eccentric has a radius less than said outer eccentric.

4. The press of claim 3 wherein the gear ratio between said sun and pinion gear is substantially one and one-half to one.

5. The press of claim 1 wherein said inner eccentric has a radius greater than said outer eccentric.

6. The press of claim 5 wherein the gear ratio between said sun and pinion gear is substantially three to one. 

1. In a press including a rotatable power shaft for reciprocating a slide connected with the power shaft through a connecting rod and connecting rod assembly said connecting rod assembly including inner and outer eccentrics, said inner eccentric being rotatably driven about a fixed center in a predetermined direction, an epicyclic gear train for rotatably driving said outer eccentric in a direction opposite to said predetermined direction about said inner eccentric, said gear train including a sun gear having a sun gear center coincidental with said fixed center, said sun gear being fixedly mounted against rotation, said gear train including a pinion gear mounted on said outer eccentric in engagement with said sun gear, said eccentrics and gear train being dimensioned for moving said connection substantially in the path of a three-lobe hypocycloid when said inner eccentric is rotatably driven.
 2. The press of claim 1 wherein said sun gear is rotatably adjustable about said sun gear center for rotatably shifting the path of the three-lobe hypocycloid.
 3. The press of claim 1 wherein said inner eccentric has a radius less than said outer eccentric.
 4. The press of claim 3 wherein the gear ratio between said sun and pinion gear is substantially one and one-half to one.
 5. The press of claim 1 wherein said inner eccentric has a radius greater than said outer eccentric.
 6. The press of claim 5 wherein the gear ratio between said sun and pinion gear is substantially three to one. 